This invention relates to the art of separation of gas mixtures, and more particularly to a new and improved process and system for separating gas mixtures by pressure swing adsorption.
One area of use of the present invention is in separating air to provide a product stream of high purity oxygen, although the principles of the present invention can be variously applied. In basic pressure swing adsorption processes and systems for separating air, adsorption is carried out at a high pressure and desorption is carried out at a low pressure. Compressed air is introduced into a fixed bed of adsorbent material and nitrogen is then preferentially adsorbed to produce oxygen rich gas product. When the adsorption bed is about saturated, the bed pressure is reduced to desorb nitrogen from the adsorbent material and regenerate the adsorption capacity. To increase the efficiency of regeneration, a purge by some of the product or an intermediate process stream often is used. To facilitate continuous operation, two or more adsorption beds are employed so that while one bed performs adsorption the other bed undergoes regeneration.
In the design and operation of pressure swing adsorption processes and systems, it would be highly desirable to provide maximum utilization of adsorbent material in the adsorption beds, reduction in energy requirements for operation of the system, a substantially constant degree of product purity, and reduction in adsorbent material requirements while maintaining a high degree of product purity, along with improved efficiency and reliability.